A composite panel consisting of a rigid or semi-rigid backer board covered with thin foam and upholstery fabric. It provides acoustic insulation, hides roof wiring, and gives the interior a finished look. Over time, heat and humidity degrade the foam backing, causing the fabric to sag and eventually drop onto the occupants.
Heard on the job
The sunroof leak ruined the headliner, so we've to drop the whole board out the back hatch to recover it.